Wireless energy transfer or wireless power is the transmission of electrical energy from a power source to an electrical load without interconnecting physical conductors. In some examples, wireless power can be supplied by employment of a transformer.
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors, the transformer's coils (e.g., windings). A varying current in a primary winding creates a varying magnetic flux, and thus induces a varying magnetic field through a secondary winding. The varying magnetic field induces a varying electromotive force (EMF), or “voltage”, in the secondary winding. This effect can be referred to as inductive coupling.